1. Field of the Invention
The present invention relates to a disposable reamer shaft that may be attached to a modular disposable spherical or tapered hollow reamer, the disposable reamer shaft being concentrically attached to a modular hollow reamer to provide wobble free rotation of the reamer tool.
2. Description of the Prior Art
Reaming of the internal canal of bones is required in many surgical procedures of orthopedic surgery. These procedures include hip replacement and shoulder replacement, and the like. Reamers are used in procedures that involve creation of acetabular bone cavities that accept a properly sized acetabular cups. Prior art reamers typically fall into two major classes: rigid and flexible shaft. Typically, reaming of the internal bone cavity is achieved through utilization of a solid spherical reamer some having provisions for discharging and collecting reamed bone fragments. Solid spherical reamers currently utilized are required to cut both cancellous bone (spongy bone) and cortical bone (hard bone). Cortical bone is generally denser and stronger, requiring an efficient cutter to machine the acetabular cavity for a proper fit of the acetabular cup. Conventional spherical reamers can cut cortical bone initially but can quickly dull after a single use, or at best a few uses. Once the reamer has dull cutting edges, it reduces the efficiency of bone cutting and in addition generates sufficient friction/heat to damage or kill the surrounding bone. These prior art solid spherical reamers are intended for multiple uses and therefore become less efficient after each surgery, resulting in poor cutting performance and bone necrosis. Dull blades also incorporate bone debris or bone cement debris into the living bone tissue, creating bone healing problems and fixation of an implanted acetabular cup.
U.S. Pat. Nos. 4,811,632, 5,100,267 and 5,299,893 to Salyer discloses a surgical reamer and a disposable acetabular reamer cup. The first patent does not disclose a disposable shaft while the second and third patents does not assure the concentricity of the cutting bowl with respect to that of the shaft.
U.S. Pat. No. 5,116,165 to Salyer discloses an acetabular reamer cup. This '165 patent does not have a disposable shaft and the arrangement used has no direct connection between the shaft and the cutting bowl other than through the base aperture. The concentricity of the cutting bowl with respect to that of the shaft is therefore not assured.
U.S. Pat. No. 5,658,290 to Lechot discloses an assembly comprising reamer spindle and reamer for surgery. The reamer comprises a cap and at least three radial rods which are arranged uniformly on the inside edge of the cap and join up integrally at the center of the cap. The reamer spindle comprises a shank on which there is fixed a reamer spindle head that is equipped with a bayonet with locking means for the securing of the reamer. The securing catches of the bayonet are intended to receive the radial rods of the reamer. The connection between the reamer rods and bayonet does not provide a precise centerline matching arrangement. The shaft is not indicated to be disposable
U.S. Pat. No. 5,709,688, as well as U.S. Pat. Nos. 6,001,105, and 6,428,543 to Salyer disclose an acetabular reamer cup and method of producing the same. The bottom has a tool driver opening coaxial and is concentric with the cutting bowl. The driver opening engages with the shaft, which drives the acetabular reamer. This form of attachment of the shaft with the acetabular reamer does not ensure alignment of axis of the shaft with that of the acetabular reamer. The acetabular reamer or the shaft is not indicated to be disposable.
U.S. Pat. No. 5,755,719 to Frieze, et al. discloses an acetabular reamer. This acetabular reamer includes a base, a first set of semi-circular blades attached to the base, and a second set of semi-circular blades also contacting said base, and crossing and intersecting with said first set of blades at right angles thereto. The base preferably comprises a circular plate having a hexagonal drive hole in the center thereof and a plurality of slots in the periphery thereof for anchoring the blades. The drive shaft is coupled to a hexagonal aperture in the base plate. This method of attachment does not align the hemispherical cutter centerline with that of the drive shaft. As such, the arrangement causes wobbliness of the cutter in the bone cavity. The shaft of the acetabular reamer is not indicated to be disposable.
U.S. Pat. No. 5,976,144 to Fishbein et al. discloses a hollow dome reamer with removable teeth. A drive shaft is connected to the base plate through an aperture in the base plate and held in place by a spring. There is no direct attachment of the shaft to the dome and this multitude of connections to the shaft does not assure that the centerline of the shaft coincides with that of the hollow dome. The shaft is not indicated to be disposable.
U.S. Pat. No. 5,980,170 to Salyer as well as U.S. Pat. Nos. 5,817,096, 5,501,686, 5,282,804, 5,236,433, 5,171,313, 5,171,312 disclose a tool driver. This tool driver has a shaft with a longitudinal axis and opposite ends. A boss is secured at one of said shaft ends by which the tool driver is connected to a rotary tool. A tool collate is secured at the other of the shaft ends by which the tool driver may be driven by a surgical hand piece having a chuck in which the collate may be positioned. The boss has a distal end surface with a groove therein. Both the groove and the distal end surface extend transversely of the axis. A pin is positioned in the groove on the axis. A latch mechanism is provided to hold a mounting bar of a rotary tool in the groove on the pin, whereby the rotary tool is held exactly coaxially of the driver during use. The rotary tool, which is used with the driver has a bar which has the same dimensions as the groove in the boss of the tool driver of the invention. The bar thus fills the slot and is complementary to the slot. The bar has a hole therein which is complementary to the pin. The pin extends coaxially of the shaft and the boss. The bar hole in which the pin of the tool driver is positioned is precisely coaxial of the axis of the tool about which the cutting edges are precisely positioned. The tool driver has a shaft appointed to receive acetabular reamer cups and patella cutters. The cutters are appointed to be connected to the tip of the shaft by means of mounting bar in the cutter and a slot in the shaft secured by a complementary pin. This method of attachment—using a mounting bar that slides into a slot—does not align the centerline of the shaft with that of the reamer. Moreover, the shaft is not indicated to be disposable.
U.S. Pat. No. 6,168,600 to Grace, et al discloses an acetabular reamer backing plate and method of use. The backing plate for an acetabular reamer assembly that has a planar surface allows for the attachment of a reamer driver. This attachment feature only uses a single point attachment of the reamer to the shaft at the edge profile of the backing plate. It is therefore subject to displacement of the shaft laterally, causing the centerlines of the shaft and reamer to be not precisely aligned. The shaft is not indicated to be disposable.
U.S. Pat. No. 6,409,732 to Salyer discloses a tool driver. This tool driver has a shaft with a longitudinal axis and opposite ends. A boss is secured at one of the shaft ends by which the tool driver is connected to a rotary tool. A tool collate is secured to the other of the shaft ends by which the tool driver may be driven by a surgical hand piece having a chuck in which the collate may be positioned. The boss is equipped with a securing device of the bayonet type having a latch mechanism, which holds the rotary tool on the boss coaxially of the driver during use. The securing device has a tapered bore extending from the distal end of the boss axially of the shaft. The rotary tool has a diametrical bar extending across a bottom tool driver opening with a centrally located circular disk therein. The disk of the rotary tool fits within the bore of the tool shaft boss so as to concentrically locate the rotary tool and the tool shaft on the same axis. The latch mechanism holds the tool driver and the tool together in this position, whereby rotary tools of a multitude of sizes can be secured concentrically to the tool shaft without holding a plurality of critical tolerances when machining the bayonet type securing device or the rotary tool bottom bar. The tool driver is a shaft with a slot on the end that receives the acetabular reamer. It deals with the details of the device for attaching the acetabular reamer to the shaft. This type of slotted attachment does not result in coaxial mounting of the reamer that is coincident with the centerline of the shaft, even though the different components of the shaft are said to be coaxially aligned. The reamer or the shaft is not indicated to be disposable.
U.S. Pat. No. 6,875,217 to Wolford discloses an orthopedic reamer assembly. This orthopedic reamer assembly includes a reamer with a generally hemispherical shell having a concave side and at least one attachment feature associated with the concave side. A driver is attachable to the reamer and has a shaft with a reamer end. A releasable collar is disposed on the reamer end, which includes a boss having at least one retaining pin. A sleeve is fitted over the boss and includes a groove that is proximate to a corresponding retaining pin. The reamer has a cavity in the reamer end with a biasing element. The biasing element biases the sleeve in a closed position respective to the boss. A release pin, which press fits into the sleeve is provided in the reamer end, and is conveyed through the cavity, with the biasing element biasing against the release pin. The orthopedic reamer assembly is a complicated attachment of design of the drive shaft to an acetabular reamer with multiple sliding parts. Since each of the sliding parts requires a sliding fit, there are inherent displacement possibilities and therefore, the centerline of the shaft is not reliably aligned with the centerline of the acetabular reamer. Moreover, the acetabular reamer or the shaft is not indicated to be disposable and requires complicated machined elements to enable a sliding fit.
U.S. Patent Application Publication No. 2003/0181916 to Wolford discloses an orthopedic reamer with flat cutting teeth. This orthopedic reamer is for cutting bone and includes a shaft and a head coupled with the shaft. The head includes a distal face with a plurality of cutting teeth. Each cutting tooth includes a hole extending through the head. At least a portion of each hole has a substantially round perimeter. A raised lip is positioned adjacent to and extends around at least part of the substantially round portion. The '916 publication discloses an orthopedic reamer with flat cutting teeth having a shaft attached to acetabular reamer cups. The reamer cups or the shaft of the '916 publication are not disposable in nature. The attachment of the acetabular reamer to the drive shaft includes a complicated mechanism and does not reliably align the centerline of the drive shaft with that of the acetabular reamer. As such, wobble free rotation is not provided.
U.S. Patent Application Publication No. 2009/0088757 to Tulkis discloses an acetabular reamer. The reamer assembly includes a tool driver and a tool. Tool driver comprises a shaft. The tool receiving end of the shaft has a flange. Formed in the flange are four L-shaped bayonet catches, which receive the tool. The tool has a body having slots. A cutter can slidably fit into the slots. When installed in the slots, the cutters project slightly above the body. The projecting portions of the cutters form the cutting edges for shaving or cutting tissue. The reamer is formed by attaching a tool to the tool driver by lowering it in the L-shaped bayonet catches. The reamer can be coupled to a drive means such as a hand drill and inserted in a body cavity. Operating the reamer against body tissue shaves of body tissue. This type of four L-shaped bayonet catches attaching a shaft to a reamer does not provide precise alignment of the centerline of the reamer and the shaft since it is a single location attachment and is subject to rotational movement. The shaft is not indicated to be disposable.
Foreign Publication No. WO 9007908 to Schelhas discloses an acetabulum reamer. Acetabulum reamer for reaming the acetabulum of the human pelvic bone prior to insertion of an artificial hip joint cup comprises a reamer head on a shaft and a spiral reaming ridge arranged about the axis of the shaft and provided with reaming devices. The outer edge of the reaming ridge is delimited by a section of a spherical surface whose axis of rotation is flush with the axis of the shaft. The acetabulum reamer utilizes a spherical head for reaming a socket in an acetabulum. The spherical shape of the multiple use reamer provides the ability to hollow out the arcuate shape of the bone joints. Significantly, the acetabulum reamer publication does not teach a disposable spherical hollow surgical reamer tool that is attached to a drive shaft with coincident centerlines.
A number of prior art patents disclose use of polymeric shaft for delivering rotational torque. These polymeric shafts generally are tubular in construction with glass fibers or carbon fibers embedded in the polymer matrix. However, these polymeric shafts are rather large in diameter and short in overall length and generally unsuited for reamer shafts, which are required to be small in diameter and long in length.
U.S. Pat. No. 4,171,626 to Yates, et al. discloses a carbon fiber reinforced composite drive shaft. A carbon fiber reinforced composite tubular drive shaft has a plurality of bonded circumferentially disposed layers of fibrous reinforcement situated within an epoxy resinous matrix material. The innermost layer has glass fibers disposed at +30° to +50° to the longitudinal axis of the shaft. The outermost layer has glass fibers disposed at +60° to 90° to the longitudinal axis of said shaft. An intermediate layer has glass fibers disposed at 0° to +15° to the longitudinal axis of said shaft. An intermediate layer has carbon fibers disposed at 0° to +15° to the longitudinal axis of said shaft. The light weight composite drive shaft is resists torsion buckling to without deleteriously influencing the critical speed of the drive shaft. The drive shaft is not indicated to be for use in attaching hollow reamers.
U.S. Pat. No. 4,248,062 to McLain, et al. discloses a drive shaft assembly and method for making same. A composite drive shaft having a hollow tubular, multi-layered fiber reinforced plastic shaft portion with a metallic sleeve inserted in and bonded thereto at least at one end, said sleeve having a universal joint connector. The tubular, fiber-reinforced plastic shaft has layers of oppositely angled resin-impregnated helical fibers at 25° to 65° to the longitudinal shaft axis and at least one layer of longitudinal fibers forming a laminate and a metallic sleeve is received within at one end and longitudinal fibers provides flexural rigidity to the laminate and oppositely angled layers provide torsional strength and inner spiral layer provides additional hoop strength to the laminate. This drive shaft assembly has a universal joint and does not connect to a hollow reamer.
U.S. Pat. No. 4,259,382 to Schwan discloses fiber reinforced composite shaft with metal connector sleeves secured by adhesive. The tubular fiber reinforced composite shaft comprises a shaft body formed of a plurality of integrally bonded circumferential plies of solidified fiber reinforced resinous material. A metal sleeve is mounted in at least one end of the shaft body. A layer of adhesive material is disposed between an outer surface of the metal sleeve and an inner surface of the shaft body to bond the sleeve to the body. This composite shaft assembly with adhesively bonded is not indicated to connect to a hollow reamer.
There remains a need in the art for a modular easy-to-assemble spherical or tapered hollow reamer for medical applications having a disposable reamer shaft. Also needed in the art is a disposable spherical hollow or tapered cutter assembly, which can be attached concentric to a reusable shaft portion that provides means for reaming of a bone cavity without wobbly movement. Further needed in the art is a cutter assembly having means for collecting bone debris and keeping the collected debris displaced from the cutting portion, so that heat generated at the bone cutting surface is minimized. Still further needed in the art is a disposable shaft for a spherical hollow or tapered reamer assembly wherein, after one use of the spherical or tapered hollow reamer, a clean contamination-free replacement shaft is provided.